As the use of many different telecommunication systems simultaneously in different locales creates greater flexibility for the user of cellular telephones, it also creates many challenges for the designers of the internal architecture of those cellular telephones. In addition to the traditional technological trends such as smaller size, lighter weight, and fewer part counts, designers are now being asked to also include greater capabilities into cellular telephones such as the ability to function at two or more different bands of the electromagnetic spectrum.
Incorporating dual mode/dual band capabilities into the radio architecture design is not a trivial process and may involve a significant change of thinking at the earliest stages of the design process.
FIG. 1 shows a block diagram of a radio architecture for a dual band cellular telephone in accordance with the prior art 100 is provided. Referring to FIG. 1, a radio transmit signal from a first band (Band #1) will pass through a driver 102, a power amplifier 104, an impedance matching network 106, a directional coupler 108, a harmonic filter 110. At this point, the signal will pass through a diplexer 112, and finally out the antenna 114. Similarly, for a radio transmit signal from a second band (Band #2) will pass through another driver 202, another power amplifier 204, another impedance matching network 206, another directional coupler 208, and another harmonic filter 210. The second signal will then pass through the diplexer 112, and finally out the antenna 114.
With this design, each of the bands have their own dedicated components. Each band has it's own impedance matching network, directional coupler, and harmonic filter. Such duplication of components may lead to a cellular telephone having additional circuitry, a high parts count, increased switching and power consumption, as well as increased volume, weight, and size.
A radio architecture design which provides a power amplifier output module for dual mode digital systems in a monolithic component and which integrates harmonic filtering requirements into an impedance matching network and which is capable of handling two discrete power amplifier drive circuits using a single coupler and a single antenna in a highly integrated multilayer ceramic package and which provides improved insertion loss and self-shielding properties would be considered an improvement in the art.